An endoscope is constituted of an image pickup distal end and a main body. The image pickup distal end includes an optical system and an image pickup device and is inserted into the body of a patient. The main body is placed outside the body and operates the image pickup distal end and acquires picked-up images. Conventionally, electrical signals have been used for communication (image transmission, etc.) between the image pickup distal end and the main body (e.g., see Patent Literature 1).
The image pickup distal end has to be detached from the main body for each surgical operation and subjected to sterilization treatment. Therefore, the main body and the image pickup distal end are connected to each other through an easily attachable/detachable connector. Here, the transmission capacity has increased because of improvements in the resolution of the endoscope, and hence the use of optical communication for the communication between the image pickup distal end and the main body has been studied.
An endoscope for medical purposes includes an insertion portion incorporating therein an image pickup device such as CCD and CMOS image sensors. By inserting the insertion portion into a body, organs inside body cavities and lesions can be observed (e.g., see Patent Literature 1). In recent years, an image pickup device having a large number of pixels, which enables higher resolution image observation to be performed, has been developed and the use of the image pickup device having a large number of pixels in the endoscope has been studied.
In a case of using the image pickup device having a large number of pixels in the endoscope, it is necessary to incorporate an optical transmission module in the endoscope in order to speedily transmit image signals between the image pickup device and a signal processing apparatus. Electrical signals of an image generated by the image pickup device are converted into optical signals at the optical transmission module and transmitted to the signal processing apparatus via an optical fiber.